Forming paper containing periodate oxidized polygalactomannan gum and paper thereof



United States Patent 3 205,125 F QRMING PAPER ONTAiNHNG PERKGDATE OXIDIZED POLYGALAQTGMANNAN GUM AND PAPER THEREOF of the anhydromannose units when these reduced ratios of periodate are employed. With guar, it is thus possible to prepare a product consisting essentially of a polyanhydromannose chain, substituted at every other number 6 position with a hydroxycarbonyl system. ggg g %gghf gfigzggg zg gg gfgfi ggffigja 2 Briefly, the invention comprises the oxidation of polypamfiml of Delaware galactornannan gum by a periodate m which from 0.01 Nonrawing Filed June 27, 1963, geLNL 290,926 mole to 0.4 mole and preferably 0.03 to 0.25 mole of 10 Cl i (C1, 152 17 periodate, more desirably about 0.1 mole, 1s used with 19 1.0 mole of anhydrous hexose unit. The oxidizing agents This application is a continuation-in-part application of which may be employed in this invention are the periodic our copending application Serial No. 47,610, filed August acids, the alkali metal salts of periodic acids such as sodi- 5, 1960, now abandoned, which was in turn a continuum and potassium periodate, and the like. ation-in-part of our application Serial No. 824,771, filed The tio of ga e to mannose in the guar p y July 3, 1959, now abandoned. is one to two. With guar, after oxidation with 0.25 mole This invention relates to the formation of paper and in periodate p anhydrous hexose unit, the ratio of galacparticular to the use of low level periodate oxidized polytose to rnannose is found to be about one to three, thus galactomannan gums in the formation of paper as a wet indicating that the galactosc is preferentially attacked by end additive. the periodate. Thus oxidation of the gum with periodic It has been discovered that polygalactomannan gums 2o acid Will Yield a Polymeric Chain of mafinose units oxidized with periodic acid or the alkali metal salts therethat are partially substituted with aldehydic functions on of in which from 0.01 to 0.4 mole of oxidizing agent are every other unit of the chain. This aldehydic function is employed per anhydrous hexose unit of said gum, provide due to the formation of carbonyl groups during the cleavimproved paper when employed as a Wet end additive in age of galactose units by the periodate. Thus the gums are the process of forming paper. The use of these oxidized sometimes referred to as aldehyde gums. products provide for improved formation of the paper Although the invention is not dependent thereon, it is sheet by aiding uniformity of dispersion of the pulp from believed that the molecular structure of the gum is changed which the paper is formed, provides in many cases imby reaction with the periodic acid with a substantial numproved dry strength and in particular are effective to prober of the anhydrogalactose units of the gum essentially vide increased wet strength. as follows using guar gum as an illustration.

CHzOH CHzOH I I O O O O- AH O.l\ v \r /0.. on OH HO l\ OH OH// I l l l I CH2 H2 H0 THzOH 0 01120?) o O in; O

OH A l I OH 11 n It is therefore an object of this invention to provide an where A is substantially improved process of forming paper. H

It is also an object of this invention to provide an improved paper.

Briefly, the invention comprises the addition to paper 0 pulp prior to sheet formation of an oxidized polygalacb may 1 b tomannan gum, in which the oxidizing agent is periodic H acid or the alkali metal salts thereof and the oxidizing agent is employed in an amount of from 0.01 to 0.4 mole of oxidizing agent per anhydrous hexose unit. Preferably o from 0.03 to 0.25 mole of oxidizing agent is employed and generally about 0.1 mole. Such oxidized products were found to have substantially only the galactose units oxidized, the mannose units being substantially unoxidized. These products are excellent wet end additives in the production of paper, generally being added in the beater, head box, fan pump or regulator box. The product is added at a level of about 0.1 to 5.0% by Weight based on the pulp.

Guar gum is a polygalactomannan gum in which the structural chain is made of D-mannose units with 1-4 linkages. A D-galactose unit is linked 16 on the average of every second D-mannose unit of the chain. The ratio of galactose to mannose is therefore 1 to 2. Locust bean gum is also a polygalactomannan gum of similar molecular structure in which the ratio of galactose to mannose is 1 to 4.

It has been found that useful products can be made by oxidizing the above systems with less than stoichiometric amounts of periodate. It has been further found that the anhydrogalactose units are preferentially attacked ahead The action of the periodate can best be illustrated by means of the followin examples:

EXAMPLE I 0.4915 g. of purified guar gum was dissolved in 50 cc. of distilled water. 0.1623 g. of sodium periodate dissolved in 10 cc. of water was added. Thi represents a ratio of 0.25 mole of periodate per mole of anhydrous hexose unit. The volume was adjusted to cc. and the mixture all-owed to stand overnight at 45 C.

The product was reduced and hydrolyzed. The unoxidized hexose units were separated by paper chromatography. A colorimetric determination showed the ratio of galactose to mannose to be 1 to 3.4, thus indicating that the attack was made preferentially on the galact-ose unit.

EXAMPLE II A sample of guar Was oxidized in a manner identical to Example I. After reduction and hydrolysis the amounts of glycerol and erythritol were determined. The ratio .9 of glycerol or erythritol was found to be 4 to 1, again indicating preferential attack on the galactose unit since glycerol would have come only from this hexose unit.

The reaction is carried out in a variety of ways such as the following general methods of preparation.

Method A The modified gums in a water soluble form can be prepared by making a dilute (0.2-2.0%) slightly acidic solution of the gum and reacting from 0.01 to 0.4 mole periodic .acid or its salts per anhydrous hexose unit of gum with the dissolved :gum. The product prepared in this manner remains water soluble and can be used as is.

Thus it is possible to take advantage of the useful properties of this product by merely mixing periodate into the dissolved and dispersed gum and allowing the oxidation to take place. The mixture could then be used as a heater additive or in other applications in the presence of the iodate which is formed during the oxidation without actually isolating the product. Periodates are expensive, however, and some means must be provided for recovering their reduced products and regenerating the periodate so that it can be used again. Further, in some applications it may be undesirable to utilize a mixture of the modified gum and the iodate. In order to recover the reduced products, it is necessary that the guar used in the reaction remain in a granular state so that it can be filtered or otherwise recovered from the reaction mixture. The filtrate in turn will contain the iodate which can be regenerated to the periodate. Granular gums can he obtained by use of Method B or C, which follow.

Method B The modified gums in a granular condition can be prepared by dispersing the gum in a solvent mixture, at room temperature or below, consisting of -70% water miscible solvent that does not react with periodic acid or its salts and 85-30% Water. The aqueous organic solvent prevents the gelation of the guar. The organic solvent used must be one that will not react with the oxidation product or in itself be attacked by the periodate. Accordingly, ketones and alcohols can be used. Illustrative of the solvents which may be employed are the dialkyl ketones such as acetone and the alkyl alcohols such as methanol, .isopropyl alcohol, tertiary 'butyl alcohol and the like in which the alkyl group has from 1 to 4 carbon atoms. A solution of 0.01 to 0.4 mole of periodic acid or its salts (preferably 0.03-0.25 mole) per anhydrous hexose unit of gum are added .to the dispersed gum. The pH should be acid or neutral but not basic. The reaction producing aldehyde gums is usually complete with /2 hour as determined by the absence of periodate. The aldehyde gum produced in this manner is relatively insoluble in hot or cold water, but will dissolve in dilute NaHSO solution.

Method C The modified gums in a granular form can also be prepared by the intimate mixing of 1 part gum with 1-3.5 parts slightly acidic water containing the desired amount of periodic acid or its salts. After the reaction is complete, the product can be washed with water, or, alternately dried and then washed with water, to remove the resulting IO; and dried. The product prepared in this manner is not water soluble but will dissolve in dilute NaHS0 The lack of solubility in water alone followed by solubility in bisulfite is typical of structures which can be formed during and after the periodate treatment. The water insoluble forms of iodate free aldehyde gums can be made water soluble by reacting them with a slight excess of 2 moles of NaI-ISO per mole of periodate used in the production of the aldehyde gum. This is readily done by intimately mixing the correct amount of bisulfite with moist aldehyde gum and drying the resulting mixture with heating. This procedure gives the bisulfite reaction compound of aldehyde gum which is readily water soluble.

The following example will illustrate the chemical reaction in which the guar gum product is not isolated and is not separated from the iodate co-reaction product.

EXAMPLE III Method A Commercial .guar gum (5.0 g., dry weight) was mixed with 500 cc. of water in a Waring Blendor. The resulting solution was made slightly acid with acetic acid. 0.33 g. NaIO was added to the sol in the Waring Blendor. The resulting sol was successfully used as a wet end paper additive without removing the residual iodate or isolating the active aldehyde gum.

The following examples will best illustrate the chemical reaction in which the guar gum is recovered as a granular material.

EXAMPLE 1V hlethod B Guar gum (0.4878 g.) was oxidized in 60% aqueous methanol solution using 0.25 mole of sodium periodate per anhydrous hexose unit. The reaction was conducted at 4 to 5 C. for 24 hours. At the end of this period the periodate was completely consumed. The mod1fied guar was in a granular condition and was isolated by filtration. The was insoluble in water and alkali indicating that a cross-linking and polymerization voccured in the presence of methanol.

EXAMPLE V Method B The same reaction was repeated in methanol with the same results. Again the product was insoluble in water and alkali.

EXAMPLE VI Method B Guar was oxidized in the same manner as outlined above except that the reaction was carried out in a 60% acetone suspension. In this case an oxidized guar gum in a granular condition was recovered which was insoluble in water but easily soluble in alkali (pH 8). Again the product was readily recovered by filtration.

EXAMPLE VII Method B g. commercial guar gum (dry weight) was placed in a mixture of 1700 cc. distilled water and 300 g. acetone. It was mixed /2 hour and cooled to about 10 C. 62 cc. of 1.0 molar periodic acid was added to the slurry over /2 hour. 400 g. of acetone was added to the slurry and the gum was collected by centrifuging. The product wa reslurried and washed four times in 1000 ml. portions of water. Each time the product was collected by centrifuging. During the washing operation the product was brought to neutrality with ammonia. The final pro-duct was dried. A portion of the dried product was dissolved in boiling dilute NaHSO solution and used successfully as a wet end paper additive.

EXAMPLE VIII Method C g. (dry weight) of commercial locust bean gum was placed in a small laboratory mixer of the Baker- Perkins type and 400 cc. of acid solution containing 0.2 mole of periodate was added over a 45 minute period. The resulting aldehyde locust bean gum product was washed three times with cold tap water. The product was collected by centrifuging after each washing. The resulting product was washed twice in 1 liter portions of acetone to remove water and dried. The product was mixed with boiling dilute NaHSO and used successfully as a wet end paper additive.

EXAMPLE LY Method C v i tory Brabender mixer and well mixed with 15.6 g. of

In order to more fully illustrate the utility of the modified gums, handsheets were prepared from bleached kraft pulp of about 650 Schopper-Riegler freeness. The pulp was made acid with HCl to a maximum pH near 4, prior to hand-sheet formation. Various wet end additives were used and all three general methods of preparation of the modified gums were employed. The organic solvent used in method B was tertiary butanol or acetone. The results obtained are shown in the following Table I. For comparison purposes results obtained with unmodified gums and other additives are included in the table.

General method of preparation 7 Product OOOUJW WOO'UOQO Commercial Guar Gum Aldehyde Corn Starch TABLE I Pounds burst per 100 pounds ream weight Moles 10; Wet approximately per hexosc Control Dry burst by burst min.

unit soaking) 1 Percent additive based on pulp solids. 2 Approximately.

NaHSO The product was then dried on a laboratory steam heated drum drier. The product was water soluble and was successfully used as a wet end paper additive.

EXAMPLE X Method C 160 g. (dry weight) of commercial guar gum was placed in a small Readco laboratory mixer and 300 cc. of slightly acid solution containing about 0.05 mole of periodate was added over an hour period. About 488 g. of product was obtained. This was dried to 215 g. in a small gas heated laboratory rotor drier. The dried product was suspended in about 850 cc. of water and collected in a basket centrifuge. The product was washed in the centrifuge with about 300 cc. of water. 830 cc. of washings containing 80% of the resulting 10; were obtained. The product was resuspended in about 1 liter of water and again collected in the centrifuge; 850 cc. of washing containing 1 0% of the resulting 10 were obtained; 430 g. of moist product were obtained. The moist product was well mixed with 18 g. of NaHSO in a laboratory mixer. It was then dried in the small gas heated laboratory rotary drier. 200 g. of product containing 14% moisture was obtained.

Carob or guar gums work equally well in all examples shown.

As with the modified guar gum, the modified locust bean gum is also useful as a wet end paper additive. The modified locust bean gum functions as a wet and dry strength additive and is normally employed as a beater additive.

The resulting products from any of these methods of preparation can be added to paper pulp to provide a paper having improved strength characteristics.

The data in Table I indicate that aldehyde gums give wet strength regardless of the method of preparation of the gum. The most useful level of periodate to use apparently lies between 0.03 and 0.25 mole, and more desirably 0.1 mole, of periodate per hexose unit of gum, although this is somewhat dependent upon the method of preparation of the aldehyde gum. This level is much lower than that necessary for preparation of aldehyde starch which is efiective as a wet strength additive. Table I also shows that the aldehyde gums are more efiective wet strength additives than aldehyde starch.

The aldehyde gums give optimum wet strength to paper where they are used at an acid pH. It is believed that this promotes the formation of hemiacetal links between the gum and the cellulose fibers.

The effects of pH in the soaking water on the wet strength of paper treated with the aldehyde gums is outlined in the following Table II.

TABLE 11 [Wet burst, lbs/ lbs. basis weight] Soaking time min.

60 min.

min.

0.1 Oxidized Guar 0.05 Oxidized Guar From the foregoing Table II it is apparent that wet strength is adequately maintained at acid or neutral pH values, but drops as the system is made very alkaline. This is an,advantage since the treated product can be repulped merely by treating the broke, trim, and Waste with alkali. Paper that is treated would also be far less likely to clog and foul cess pools and sewer systems. Waste which contains wet strength paper made with aldehyde gum can also be easily repulped.

The use of aldehyde gums also has other advantages in the paper making operations. Aldehyde gums can be transported at nearly 100% solids. The bisulfite adduct is easily dissolved, and can be easily converted to the free aldehyde gum with mineral acid. In time, the felts used in making wet strength paper with the usual wet strength resins become clogged with excess resin and become harsh. They are not easily cleaned. Where aldehyde gums are used, the felts can be easily cleaned by washing them in an alkaline bath or using an alkaline felt shower periodically.

Having thus described our invention, we therefore claim:

1. In a process of forming paper, the step of adding to the paper pulp prior to sheet formation from 0.1 to 5% of an oxidized polygalactomannan gum, the oxidizing agent being selected from the group consisting of periodic acid and the alkali metal salts thereof, said oxidizing agent being employed in an amount of from 0.01 to 0.4 mole per anhydrous hexose unit in said gum.

2. A process as defined in claim 1 in which said oxidizing agent is employed in an amount of 0.03 to 0.25 mole per anhydrous hexose unit.

3. A process as defined in claim 1 in which said oxidizing agent is employed in an amount of about 0.1 mole per anhydrous hexose unit.

4. A process as defined in claim 1 in which said polygalactomannan gum is guar gum.

5. A process as defined in claim 1 in which said polygalactomannan gum is locust bean gum.

6. A paper sheet having absorbed therein from 0.1 to 5.0% of an oxidized polygalactomannan gum, the oxidizing agent being selected from the group consisting of periodic acid and the alkali metal salts thereof and being employed in an amount of from 0.01 to 0.4 mole per anhydrous hexose unit in said gum.

7. A paper sheet as defined in claim 6 in which said oxidizing agent is employed in an amount of 0.03 to 0.25 mole per anhydrous hexose unit.

8. A paper sheet as defined in claim 6 in which said oxidizing agent is employed in an amount of about 0.1 mole per anhydrous hexose unit.

9. A paper sheet as defined in claim 6 in which said polygalactomannan gum is guar gum.

10. A paper sheet as defined in claim 6 in which said polygalactomannan gum is locust bean gum.

References Cited by the Examiner UNITED STATES PATENTS 2,685,508 8/54 Spear 162-178 2,767,167 10/56 Opie et a1. 260209 2,803,558 8/57 Fronmuller 260209 2,880,236 3/59 Mehltretter et a1 260-233.3 2,885,394 5/59 Barry et al 260209 2,988,455 6/61 Rosenberg et al 260209 3,062,703 11/62 Hofreiter et al. 162175 3,086,969 4/ 63 Slager 260209 3,098,869 7/63 Borchert 260209 OTHER REFERENCES Meller: The Effect on Paper Wet Strength of Oxidized Starches as Beater Additives, TAPPI, vol. 41, No. 11, November 1958, pp. 684-686.

TAPPI, vol. 33, No. 2, February 1950, pp. 77-81.

Mehltretter et al.: Electrolytic Preparation of Periodate Oxystarch, Industrial and Engineering Chemistry, vol. 49, No. 3, March 1957, pp. 350-354.

Jeanes et al.: Periodate Oxidation of Dextran, Journal of American Chemical Society, vol. 72, June 1950, pp. 2655-2658.

Walder: The Polysaccharides, Food, December 1948, PP. 356, 357, and 360.

DONALL H. SYLVESTER, Primary Examiner.

MORRIS O. WOLK, Examiner. 

1. IN A PROCESS OF FORMING PAPER, THE STEP OF ADDING TO THE PAPER PULP PRIOR TO SHEET FORMATION FROM 0.1 TO 5% OF AN OXIDIZED POLYGALACTOMANNAN GUM, THE OXXIDING AGENT BEING SELECTED FROM THE GROUP CONSISTING OF PERIODIC ACID AND THE ALKALI METAL SALTS THEREOF,SAID OXIDIZING AGENT BEING EMPLOYED IN AN AMOUNT OF FROM 0.01 TO 0.4 MOLE PER ANHYDROUS HEXOSE UNIT IN SAID GUM.
 6. A PAPER SHEET HAVING ABSORBED THEREIN FROM 0.1 TO 5.0% OF AN OXIDIZED POLYUGALACTOMANAN GUM, THE OXIDIZING AGENT BEING SELECTED FROM THE GROUP CONSISTING OF PERIODIC ACID AND THE ALKALI MTALALTS THEREOF AND BEING EMPLOYED IN AN AMOUNT OF FROM 0.01 TO 0.4 MOLE PER ANHYDROUS HXOSE UNIT IN SAID GUM. 